|Version 4 (modified by 8 years ago) (diff),|
Trac is strong in basic, individual and small-team task management but lacks features for heavy-duty project management a la Microsoft Project, Project Manager Workbench, etc. This page discusses those missing features and how they can best be realized.
Trac has three Gantt chart plugins:
- seems complex and stale.
- is a very simple Gantt chart implemented in a formatted text region. It is manually edited, not data-driven.
- has potential but has some funky fields (e.g., Due to Assign) that don't seem to be appropriate to what we want to do with a Gantt chart.
There is a Google Gadget Gantt chart which might be leveraged for the visualizations once the data is made available.
Gantt Chart Components
In its most basic form, a Gantt chart shows:
- Self-contained units of work
- Relationships between tasks that constrain when they can be done
- Dates by which one or more tasks must be completed
It may also show resource assignments and progress in tasks. It often includes a "today" line to show where a project stands. (If the project is on schedule, all tasks to the left of today are complete and any task that spans today has a progress bar to the right of today.)
A Gantt chart may also show slack time for tasks, how much they can slip before affecting the overall schedule.
Each Gantt chart component or feature requires data to support it. For Trac-based project management, this data is often in addition to the core ticket data.
Core ticket fields include:
- type (bug, task, enhancement, etc.)
- time (when the ticket was created)
- owner (who is working on it)
- reporter (who wrote the ticket)
- milestone (what milestone this ticket is part of)
- status (new, assigned, ..., closed)
- summary (short description)
Core milestone fields include:
- due (date and time)
- completed (treated as a Boolean: open or closed)
For a simple Gantt chart, we may use the following ticket fields:
- owner (the resource assigned to the task)
- milestone (when the task is due)
- summary (short description)
In addition, a task must have:
- estimate (expected work require to complete task)
- percent complete
It may also prove useful to note that a resource may not be applied 100% to a task.
While Gantt charts typically show percent complete, this can be computed from hours remaining vs. total estimate or hours worked vs. total estimate. We will not, necessarily, store percent complete. It is intuitive for display and analysis but difficult for data entry.
There are four general types of dependencies for tasks:
- Task B may have to start after task A. That is, B can't begin until A is done, perhaps because it uses a product of task A as a raw material.
- Task A may be composed of tasks B, C, and D. That is, tasks B, C, and D are subtasks of task A.
- Task A may have to start with task B (but they may end independently). For example, auditing someone's work may start when their work starts but may involve analysis and reporting after that work is done.
- Task A may have to end with task B (though they may start independently).
Each of these relationships has an inverse relationship in the other task.
- If B starts after A, then A ends before B.
- If A is composed of B, C, and D, then B, C, and D are part of A.
- If A starts with B, then B also starts with A.
- If A ends with B, then B also ends with A.
While generally useful, the starts with and ends with dependencies are somewhat more esoteric than the others and implementation may be deferred.
A Gantt plugin for Trac should analyze ticket dependencies and produce an interactive, explorable Gantt chart showing task progress and project status.
By "project", I mean a set of related milestones. Perhaps a software project has a Design Phase, an Alpha Release, a Beta Release, and a General Release. Each would be a milestone with a target date and tickets to complete the work for that milestone. There must be a way to specify which milestones to include either listing explicitly or by giving a pattern or substring filter.
The chart should be able to show all tickets (though that may be a very complex chart) or alternately all those tickets matched by a (query | report) or any other ticket group provider. A "chart these" button on a report page would be very nice.
The chart should support interactively "folding" groups of tasks to hide detail.
Tasks in the chart should be links to the tickets they represent.
To effectively display project progress, tickets must have estimated and actual times as in the TimingAndEstimation plugin. Each task's bar in the chart should show actual hours.
The chart should have a Today line
It is also desirable to have loop detection to error-proof the tool used to create dependencies.
It would be nice to be able to choose an As Late As Possible or As Soon As Possible algorithm for laying out tasks.
The chart (or an accompanying report or tool) should aid in resource leveling by (at least) showing overcommitted resources.
MasterTicketsPlugin supports starts after/ends before dependency (but calls it blocks and blocked by).
The SubTickets page talks about adding composed of/part of-type dependency. Can this be done in a plugin like MasterTickets or must it be in the core?
TimingAndEstimationPlugin and TracHoursPlugin add estimated and actual hours fields to tickets. There is some disagreement about whether the estimate is the remaining time (so total estimated time is actual + estimate) or total time (so remaining time is estimate - actual). A Gantt chart typically wants estimate and percent complete. It is possible to extract this from either recording convention and we should likely allow either convention via a configurable interface.
There seems to be a consensus that grandiose project management features for Trac should be implemented with a combination of plugins which provide useful functionality on their own. The following plan assumes that approach.
- Fork MasterTickets as TicketDep (or something) and add composed of/part of dependencies and means to create them. Plan for but do not yet implement starts with and ends with dependencies.
- Specify the interfaces necessary for a scheduling plugin to use dependencies, estimates, and time worked to determine project schedule.
- Consider adding a percentage available when scheduling resources.
- Specify the interfaces necessary for a Gantt chart to get data from tickets.
- Each task must have a name, duration, percent complete, and start or end. (The start or end comes from schedule calculations, not direct ticket data.)
- Implement those interfaces on top of TimingAndEstimationPlugin.
The bulk of this page was prepared by Chris Nelson who makes no claim to be a certified project planner or anything of the sort. It is based on his understanding of project management after 25 years of software development.
simple-gantt.PNG (7.0 KB) - added by 8 years ago.
A simple Gantt chart
gantt-progress.PNG (7.9 KB) - added by 8 years ago.
Gantt chart with progress bars
gantt-resource.PNG (11.0 KB) - added by 8 years ago.
Duration longer than work due to resources
critical-path.PNG (9.9 KB) - added by 8 years ago.
roll-up-1.PNG (12.7 KB) - added by 8 years ago.
Rolling up subtasks - 1
roll-up-2.PNG (9.6 KB) - added by 8 years ago.
Rolling up subtasks - 2
resource-utilization.PNG (5.9 KB) - added by 8 years ago.
Resource utilization chart
today.PNG (15.9 KB) - added by 8 years ago.
Gantt w/ "today" (progress) line
slack.PNG (15.4 KB) - added by 8 years ago.
Slack time illustration
progress-line.PNG (15.9 KB) - added by 8 years ago.
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